The specific aims of the proposed work are to study: 1. The role of gonococcal pili in the host-parasite relationship; a. The role of pili in the sticking of gonococci to mammalian cells; b. Characterization of the mammalian receptor of gonococcal pili; c. Species and organ distribution of the pilus receptor; 2. Immunochemical analysis of the outer membrane of the gonococcus; a. Further studies on the purification of the outer membrane; b. characterization of low molecular weight outer membrane protein. BIBLIOGRAPHIC REFERENCES: Gotschlich, E.C. Immunology of gonococcal infections--immunization prospects. In Sexually Transmitted Diseases. Editors: Catterall, R.D. and Nicol, C.S. Academic Press, New York, p. 105-111, 1976. Munford, R.S. and Gotschlich, E.C. Iodination of Escherichia coli with chloramine T: selective labeling of the outer membrane lipoprotein. J. Bacteriol. 130:775-780, 1977.